Smart Drugs for Complex Diseases

The discovery of new therapeutic uses for drugs that have been developed for other indications is known as "drug repurposing." The considerable risks inherent in development are greatly reduced because the repurposed drug has been used in a large number of patients often for many years. This means that it has a well-known safety and pharmacokinetic profile. Moreover, the pharmacology, toxicology, formulation and early clinical trials have been completed greatly reducing costs and shortening the pathway to market. It is now accepted that repurposing offers a much better risk-return trade-off compared with other drug development strategies.

The focus in drug development until recently has been on a single target associated with a particular pathological mechanism. However, it has been found that low-affinity, multi-target drugs have a lower prevalence and a reduced range of side effects than high-affinity, single-target drugs while at the same time having greater efficacy. This has led to the development of single compound multifunctional drugs that simultaneously target a number of different pathological mechanisms that are associated with complex diseases such as heart failure, stroke, diabetes, obesity, rheumatoid arthritis, cancer, major depression and Alzheimer's disease. It has now been found that an increasing number of repurposed drugs derive their therapeutic benefit by interacting with multiple targets. These drugs offer a new approach in the development of treatments for complex diseases.